Intermittency and Correlations at LEP and at HERA

A review on recent investigations of local fluctuations and genuine correlations in electron-positron annihilations at LEP and in positron-proton collisions at HERA is given

The ridge effect and three-particle correlations

Pseudorapidity and azimuthal three-particle correlations are studied based on a correlated-cluster model of multiparticle production. The model provides a common framework for correlations in proton-proton and heavy-ion collisions allowing easy comparison with the measurements. It is shown that azimuthal cluster correlations are definitely required in order to understand three-particle correlations in the near-side ridge effect. This is similar to the explanation of the ridge phenomenon found in our previous analysis of two-particle correlations and generalizes the model to higher-order correlations.Comment: 16 pages, 7 figures. arXiv admin note: text overlap with arXiv:1610.0640

Searching for hidden sectors in multiparticle production at the LHC

Most signatures of new physics in colliders have been studied so far on the transverse plane with respect to the beam direction. In this work however we study the impact of a hidden sector beyond the Standard Model (SM) on inclusive (pseudo)rapidity correlations and moments of the multiplicity distributions, with special emphasis in the LHC results.Comment: Presentation given at ICHEP 2014 Valenci

Effective-energy universality approach describing total multiplicity centrality dependence in heavy-ion collisions

The recently proposed participant dissipating effective-energy approach is applied to describe the dependence on centrality of the multiplicity of charged particles measured in heavy-ion collisions at the collision energies up to the highest LHC energy of 5 TeV. The effective-energy approach relates multihadron production in different types of collisions, by combining, under the proper collision energy scaling, the constituent quark picture with Landau relativistic hydrodynamics. The measurements are shown to be well described in terms of the centrality-dependent effective energy of participants and an explanation of the differences in the measurements at RHIC and LHC are given by means of the recently introduced hypothesis of the energy-balanced limiting fragmentation scaling. A similarity between the centrality data and the data from most central collisions is proposed pointing to the central character of participant interactions independent of centrality. The findings complement our recent investigations of the similar midrapidity pseudorapidity density measurements extending the description to the full pseudorapidity range in view of the considered similarity of multihadron production in nucleon interactions and heavy-ion collisions.Comment: Same as published versio

Describing dynamical fluctuations and genuine correlations by Weibull regularity

The Weibull parametrization of the multiplicity distribution is used to describe the multidimensional local fluctuations and genuine multiparticle correlations measured by OPAL in the large statistics $e^{+}e^{-} \to Z^{0} \to hadrons$ sample. The data are found to be well reproduced by the Weibull model up to higher orders. The Weibull predictions are compared to the predictions by the two other models, namely by the negative binomial and modified negative binomial distributions which mostly failed to fit the data. The Weibull regularity, which is found to reproduce the multiplicity distributions along with the genuine correlations, looks to be the optimal model to describe the multiparticle production process.Comment: 10 pages, 2 figure

Probing Brane-World Scenarios with Vacuum Refraction of Light Using Gamma-Ray Bursts

We argue that in fat brane-world scenarios the light propagating in vacuum will, because of massive ``Kaluza--Klein'' (KK) excitations, experience a refraction. The motion of a photon inside a fat brane can be decomposed in the longitudinal and transverse directions with respect to the surface of the brane. Since the light observable propagation is related only with the longitudinal motion, the obsered speed of light depends on the value of the momentum transverse fraction contributing as the massive KK excitations. This is directly connected with the energy of the particles emitting the light, and hence with the frequency of the light itself. Using recent results on the arrival times of radiation of different energies from the measurements of gamma-ray bursters with known redshifts, we establish the limit M>620 TeV on the inverse thickness of the brane, and thus on the masses of the KK excitations. This limit exceeds by at least one order of magnitude the typical energy scale currently in use to characterize brane phenomena in the realm of future colliders

Event patterns from negative pion spectra in proton-proton and nucleus-nucleus collisions at SPS

Rapidity-dependent transverse momentum spectra of negatively charged pions measured at different rapidities in proton-proton collisions at the Super Proton Synchrotron (SPS) at various energies within its Beam Energy Scan (BES) program are investigated by using one- and two-component standard distributions where the chemical potential and spin property of particles are implemented. The rapidity spectra are described by a double-Gaussian distribution. At the stage of kinetic freeze-out, the event patterns are structured by the scatter plots in the three-dimensional subspaces of velocity, momentum and rapidity. The results of the studies of the rapidity-independent transverse mass spectra measured at mid-rapidity in proton-proton collisions are compared with those based on the similar transverse mass spectra measured in the most central beryllium-beryllium, argon-scandium and lead-lead collisions from the SPS at its BES energies.Comment: 17 pages, 9 figure

Cosmological analogies in the search for new physics in high-energy collisions

In this paper, analogies between multiparticle production in high-energy collisions and the time evolution of the early universe are discussed. A common explanation is put forward under the assumption of an unconventional early state: a rapidly expanding universe before recombination (last scattering surface), followed by the CMB, later evolving up to present days, versus the formation of hidden/dark states in hadronic collisions followed by a conventional QCD parton shower yielding final-state particles. In particular, long-range angular correlations are considered pointing out deep connections between the two physical cases potentially useful for the discovery of new physics.Comment: 9 pages, 5 figure

Two-particle angular correlations in the search for new physics at future e+e−e^+e^- colliders

The analysis of angular particle correlations can yield valuable insights into the initial state of matter in high-energy collisions, thereby potentially revealing the existence of Beyond the Standard Model scenarios such as Hidden Valley (HV). In this study, we focus on a QCD-like hidden sector with relatively massive HV quarks ($\lesssim 100$~GeV) which might enlarge and strengthen azimuthal correlations of final-state SM hadrons. In particular, we study the formation and possible observation of \textit{ridge-like} structures in the angular two-particle correlation function at future $e^+e^-$ colliders, with a much cleaner environment than in hadron colliders, such as the LHC.Comment: Talk presented at the International Workshop on Future Linear Colliders (LCWS 2023), 15-19 May 2023. C23-05-15.